What is the Best Glue For Segmented Turning
Segmented turning is a process of creating a turned object from many segments of wood, and the structural integrity is solely reliant on the glue joints that make up that object.
Choosing the best glue for your segmented turning is therefore a critical step in the design process in every item created with this method of wood turning.
We turn quite large objects when needed, and because we sell the items we turn to customers who look for the unique and special attributes that come with our items, it is vital that we get this process right.
This post is about matching the appropriate glue to the right project. I hope you find it worthy of your time.
We use the segmentation technique as it allows us to design products that are not possible in solid wood turning, at least in a consistent manner.
Approaching these vases from a business perspective demands reliability and effectiveness.
While selling our products at many markets we have been often asked about the glue we use and the process of segmented turning.
We can’t be with you to explain our thoughts on glues and joint quality so we have decided to share it online for all.
It takes time, study and practice to understand the forces at play when two or more pieces of wood are joined together using glue.
It is a necessary thought process to determine the end use of the item and the expected climatic conditions the item will be subjected to, and it is good practice to plan out the project before any wood is dressed, cut, or turned and this includes considering what glue is best for segmented turning.
There are logical steps that require your attention before laminating any wood together. These are below.
How to choose the best glue for segmented turning.
The list below is what you might consider as you plan your project.
- The type of wood and its acceptance to take glue.
- The sizes of the individual segments.
- The physical size of your planned segmented turning.
- The possible climatic factors that the piece could be subjected to when complete.
- The available time for glue-up. Your glue choice should give you time to clamp in place before it sets.
- The VOC levels need to be known and compensated for.
- The clamping methods available are suitable. Some glues demand very tight joints to be effective where others have gap filling abilities.
- The items potential to be in contact with food.
- The finish to be applied as this acts as a long term moisture barrier.
The sections below address the listed items in FAQ format.
1. Can any wood be glued?
This addresses the first item on the list above.
Every wood can be glued although some need extra attention and treatment to ensure a good bond.
Some woods have oils that can make gluing problematic like Teak, some Eucalypts, and others.
It is therefore recommended to wipe the surfaces to be joined with a cleaner like alcohol just prior to glue-up. Some woods only need a freshly machined face to take a glue.
Research your situation and treat the wood as if it will cause trouble and you will be ok.
2. Does wood size affect glue?
All woods swell and move with moisture so yes wood size does matter.
Generally speaking, segmented turning is segments of wood that are glued end-grain to end-grain.
This grain direction is the one that swells the least so it is not the end to end joint that is of real concern here. It is the side grain joints as each ring is stacked upon the previous ring.
If the same species of wood is used then you should be alright because they will react the same.
If you are inserting rings of differing densities as a feature and the segments are large then you might have problems down the track if environmental moisture is allowed to get at the wood after the project is completed and finished.
One ring will swell more than the other. Small segments shouldn’t have as much trouble.
3. How long before wood glue sets?
This is directly related to your choice of glue and we have a list of them below.
All glues have a limited amount of time before they set-up and are unworkable. It can be measured in seconds or tens of minutes.
We need to know what the typical working time is for the glues you are considering and then consider the size of your project as the larger the piece the more time you will need to ensure good joints.
4. Do seasons make wood swell?
Yes, the seasonal changes in humidity have a huge effect on wood.
Long after the glue has cured and the project is complete, the wood will continue to move.
Sealing the project will go some way to slowing this down but depending on where your project is heading off to, it might be wise to consider a glue that has some “creep” in it to help compensate for wood movement down the line.
5. Are wood glues dangerous?
All glues are harmful to a degree while they are in an uncured form.
Once curing has taken place most are safe for segmented turning, and it is while using the glue where the dangers present themselves.
Some glues are toxic at skin contact while others expel VOC’s or volatile organic compounds into the air. Do your research on your glue of choice and follow the warnings and guidelines for safe use.
Because a glue is safe once cured do not assume it is an appropriate glue for your project. Consider all of the variables we address in this article first.
6. What clamps are needed for segmented turning?
The clamps you need are ring clamps that are adjustable and in good condition. General woodworking clamps are used for stack gluing the rings together.
The clamping methods you will employ should match the requirements of the glue that is applicable to your segmented turning project.
More clamps are better than just enough and the end result will benefit greatly if the appropriate clamping tools and methods are used.
Sometimes you have to be creative (which really is just a part of woodwork anyway) and it can get interesting when you don’t have what you need available. You make things as you go.
A good example of this is the image below of the clamps on a floor vase. You should notice the ledge we left available as a clamping point as we had run out of clamp length.
The risks that turning glued pieces can attract need to be addressed.
- Operator risk while turning on the lathe. The integrity of the glue joints is vital.
- VOC levels and effects of skin contact with glue. Masks and gloves should be used as per safety data sheets of the chosen glue.
- End user risk; product longevity. The object needs to perform as expected for its service life.
- Environmental risks associated with cleanup.
We have a list of the common glue types below. To filter what glue is best for your situation you should consider the lists above and match the attributes of the glue to the task.
Titebond 1,2,3
T1 is an aliphatic resin , or carpenters glue.
T2 is a crosslinking PVA.
T3 is a polymer, Technical link here
PVA
Polyvinyl acetate is a type of aliphatic resin similar to titebond 1
Epoxy
Some woods perform poorly with this glue. Very stiff joint.
Hide
Susceptible to moisture
Resorcinol-Formaldehyde
Very good. Has health risks during application. Can be difficult to obtain.
Urethane
Can be used in humid environments during construction. Slight gap filling ability.
CCA
Very stiff glue, poor choice for segmented turning if venturing into larger objects. Has been used in segmented pen turning with some success.
Glue type specifics to consider.
The table below gives the general conditions that each glue requires and presents to the wood worker.
| Glue | Gap fill | Clean up | Creep | Work Time |
|---|---|---|---|---|
| Titebond 1 | Low | Water | Low | 4-6 mins |
| Titebond 2 | Low | Water | Low-med | 3-5 mins |
| Titebond 3 | Low | Water | Med | 8-10 mins |
| PVA | Low | Water | Low-med | 4-6 mins |
| Epoxy | Med | Solvent | No | variable |
| Hide | Low | Water | No | variable |
| Resorcinol | Low | Water | No | 2-4 hrs |
| Urethane | Low/med | Solvent | No | variable |
| Superglue | Low | Solvent | No | < 1 min. |
You can see the data on creep, and while many woodworkers try to avoid this behavior, we think that it can beneficial for the long term integrity of the turned piece, within reason.
We take this view because of information within the study mentioned in a relevant post here “is epoxy glue good for wood“. and also from personal experience of moving from a very humid climate to a very dry one and watching our furniture self-destruct in real time.
So far, every thing discussed in this article is based on the premise that the wood being used is dry, and for those who are in a hurry and cannot wait for the wood they have to dry properly we have included the information below.
Can wet wood be glued for segmented turning?
Wet wood is able to be glued under certain circumstances but they do not apply to segmented turning at all.
The elephant in the room for woodworkers in particular is moisture and this should be considered on two fronts. The first is the moisture content of the wood you intend to use and the second is environmental moisture once the project is completed.
The accepted level for moisture content for segmented turning is 12-15% and most of the glue manufacturers formulate their product and do extensive testing at or around those levels.
To achieve reliable outcomes it is recommended that you abide by the guidelines for consistency.
If large objects like the floor vases we turn are involved, then dry wood is mandatory for the safety aspect. We don’t need a vase “de-constructing” at 500rpm while the woodturner (me) is working on the item.
Environmental moisture is mostly out of your hands and the best you can do is try to mitigate the potential for damage from this vector. When choosing the glue, consider using a type that has a small degree of flexibility after curing.
PVA glues have this attribute however a crosslinking PVA is better than basic yellow glue.
If you expect movement from environmental moisture you might want to consider avoiding rigid glues like epoxy and similar.
It is the moisture levels that cause the damage to the joints from the cycling of moist to dry to moist and back again. This can cause fatigue in the joint and eventually it may let go.
If the environment is constant then the choice of glue is far simpler.
A good study on the effects of moisture on wood is linked here. Here is a snippet
“Moisture is arguably the most important factor affecting the performance and service life of wood and wood products. Moisture affects the dimensional movement of wood and wood products; under certain conditions, moisture change can result in major dimensional change.”
As you put your project into action, consider the potential end grain issues with your glue. End grain is never a good option for any glue but should hold if handled carefully until you have some side grain stability to help support the joint.
When we glue a layer/ring of segments we apply two coats to the end-grain cuts.
The first disappears into the grain and really does nothing but allow the second coat to sit on the surface longer for clamping.
It is capillary action from the wood fibers that draws the glue into the wood. We recognize that this is a weak joint and treat the component once cured accordingly.
Some woods have an oily or resinous surface when cut and require a wipe with a solvent prior to gluing. We use a methylated spirits as it cleans up and evaporates quickly.
Allowing a cleaning agent to sit for too long on a glue joint may weaken the integrity of any existing glue joint in certain circumstances.
Just think about the stresses that the glue joint will be under as you spin the blank and if you are anything like me you will be pretty fussy.
While the gluing stages are underway, follow the recommended curing times as stated on the containers. Clamping during construction is mandatory for all glues but some demand very close joints to perform as advertised.
If there are any doubts on a particular joint, we recommend that it be sorted out before glue is applied. Re-cut or replace the segment to avoid issues. We will add a day or so to certain jobs just for the sleep-at-night factor and there is a good reason for this.
In our case, we turn our vases mounted only on a faceplate. We don’t use a tail-stock and if you visit our home page you will see the size of our vases. We rely totally on the connection provided by glue.
Having said that, the size of the work piece also plays a part in glue choice. The bigger the project the more imperative it is to get the glue choice right.
The stresses of spinning a vase with it mounted just on a faceplate are extreme so a good glue choice is a must.
Our example shows the importance of the joints between segments needing to be tight and accurate so the glue can perform as demanded.
So to finish up, to successfully undertake and complete a segmented project you must understand the forces and dynamics involved during the glue-up stage, the turning stage, and then also consider the future risks from movement that the finished product will face.
Get all of this sorted out before you start and you are well on the way to adding a wonderful skill to your collection.
Just for the record, we use Titebond 3.
Article written by Tim Blanch as part owner of Pickers Ridge Hardwood Designs. He is a qualified Carpenter/Joiner and has been turning for over 25 years.